planetarium

American  

[plan-i-tair-ee-uhm] / ˌplæn ɪˈtɛər i əm /

noun

• planetariums,
  plural
• planetaria
  plural

1. an apparatus or model representing the planetary system.

2. a device that produces a representation of the heavens by the use of a number of moving projectors.

3. the building or room in which such a device is housed.

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planetarium British  

/ ˌplænɪˈtɛərɪəm /

noun

1. an instrument for simulating the apparent motions of the sun, moon, and planets against a background of stars by projecting images of these bodies onto the inside of a domed ceiling

2. a building in which such an instrument is housed

3. a model of the solar system, sometimes mechanized to show the relative motions of the planets

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Other Word Forms

Noun Inflected Forms

• planetaria
  plural
• planetariums
  plural

Etymology

Origin of planetarium

1765–75; < New Latin, noun use of neuter of Latin planētārius planetary; cf. -arium

Explanation

A planetarium is a theater where you can look at images of planets, stars, and other celestial bodies on the dome-shaped ceiling. Planetariums host school field trips by day, and can even host Pink Floyd laser light rock shows by night. Use the noun planetarium for the projector that shines light onto the surface of the building's dome, recreating solar systems and constellations — and also for the building itself, where such a show is put on. Because planetarium is a Modern Latin word (from the roots planeta, or "planet," and -arium, "a place for,"), its plural can be either planetariums or planetaria.

Example Sentences

See Examples For:

planetarium planetaria planetariums

It had an observatory and planetarium and featured custom-built domes, specialized solar-observation telescopes, and a natural science education centre.

From BBC ● Aug. 13, 2026

It will include a 360 degree planetarium as well as a gift shop and small cafe.

From BBC ● Mar. 3, 2026

That’s what happens when you have a payroll of $350 million and use it to amass more stars than the average planetarium.

From The Wall Street Journal ● Dec. 16, 2025

A 37-year-old convict, who had more than a year still to serve for theft, fled on November 14 during an outing with fellow prisoners to the city's planetarium.

From Barron's ● Nov. 28, 2025

My class went on a field trip to the planetarium.

From "Shine!" by J.J. and Chris Grabenstein

Eye of the Dream is an adaptation of this remarkable library of metadata, an audio-reactive Kaleidoscopic film for 360 domes and planetaria.

From The Verge ● Aug. 18, 2021

There are now six Zeiss planetaria spotted across the country.*

From Time Magazine Archive

A feature of the Buhl star chamber with which Director Stokley is particularly Punch-pleased is an engineering stunt unique among the world's planetaria.

From Time Magazine Archive

"I heard about planetaria, read about them, thought it would be well for Philadelphia to have one," he explained.

From Time Magazine Archive

In addition to planetaria and similar mechanisms, Father Hahn produced two extraordinary astronomical, tall-case clocks, both of which survive in public museums.

From The Borghesi Astronomical Clock in the Museum of History and Technology Contributions from the Museum of History and Technology, Paper 35, the Smithsonian Institution United States National Museum Bulletin 240 by Silvio A. Bedini

An alternative kind of venue is offered by Cosm, which emerged after a merger involving Evans & Sutherland, a company that developed digital projection technology widely used in planetariums and science centres.

From BBC ● Mar. 30, 2026

Cosm — a name blending cosmos and colosseums — “is a nod to our history and heritage of great scientists and planetariums and engineers,” Terry says.

From Los Angeles Times ● Sep. 26, 2023

His creations, which ranged from tabletop size to more than 40 feet high, resembled a combination of planetariums, construction girders, carnival rides and pinball machines.

From Washington Post ● Jul. 31, 2021

Only groups or astronomical organizations, like clubs or planetariums, that register on a website to be set up this fall will be eligible for the fun.

From New York Times ● Aug. 4, 2014

As such they were comparable to the orreries of the 18th century and to modern planetariums; that they also showed the time and rang it on bells was almost incidental to their main function.

From On the Origin of Clockwork, Perpetual Motion Devices, and the Compass by Derek J. de Solla (Derek John de Solla) Price